I've mentioned before that the emissions and vacuum systems in my truck were butchered by the previous owner. I've been slowly piecing everything back together and it is almost complete again. Today I went to a junkyard in the middle of nowhere and found several things that I needed, including the piece for the intake that goes from the front of the truck (fresh air) to the air filter box. Now instead of sucking in all that hot air directly off the header my motor can actually breathe, hoping that helps.

All together I collected 7 items and he charged me $10, I thought it was a hell of a deal. Anyway, on to the question..

Two of those items were the TAB and TAD solenoids. I couldn't find a truck complete enough to show me where those vacuum lines were going. I was hoping someone here could point me in the right direction with pictures or a good description. Thanks in advance for any help.

 

Does anyone maybe know of a link with a vacuum diagram for our trucks? When I got the truck basically everything had been plugged off and every vacuum solenoid has been removed. It has been a complete guessing game now where all the lines are running and I am pretty hopeful that once I get it figured out my 7 mpg might improve.

 

Tab/Tad solenoids get mounted on the bracket next to the coil, vacuum comes from the tree and is then metered by these solenoids to the TAB and TAD valves which are typically down behind and to the passenger side of the engine on the 1/2 ton trucks but on HD trucks there is often a combo TAB/TAD valve on top of the motor beside the upper intake. Which version of this system are you re-installing?

 

Ok good, pretty much everything on the vacuum tree is plugged off so that gives me a good start. I'm installing this on the truck in my signature, so I need to locate that tad/tab combo valve. Thanks for the help.

 

Alright, one more question. Which vacuum lines are important to smooth operation of this motor? Like I said, most are plugged off on the vacuum tree. There is another one plugged on the throttle body, I would think that is important. I know a lot of the emissions systems can be disconnected with little effect to the operation of the motor, so right now I want to focus on getting the important lines hooked up.

I hate vacuum and electrical systems... Makes me miss all the pre 1975 trucks I used to own.

 

The short answer is none of them except the one to back of the C6 transmission if you have that transmission.

Vacuum for the TAD & TAB comes from the vacuum can on the passenger fender. This is the same vacuum source (black vacuum line) that feeds the EGR solenoid that is mounted beside the TAD & TAB solenoids.
The vacuum can is feed from the vacuum tree with a red vacuum line.
The TAD & TAB solenoids are part of the Thermactor Systems (Secondary Air Injection).

The throttle body vacuum port is feed from a solenoid valve and it handles gas fumes from the fuel tank. It is part of the Evaporative Emission (EVAP) Systems.

Is your truck under 8500 GVW or over 8500 GVW?

All of these are covered in the diagram below.



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Thank you, looks like that's about everything I needed.

 

If you don't have emissions tests to pass and in particular if the stock cat is gone the the whole thermactor(air injection) system is redundant and can be eliminated without affecting engine operation or emissions with an aftermarket cat installed.
The only vacuum the vehicle really needs is for cruise and HVAC diverter/blend door operation which should be supplied via the vacuum canister, and to the brake booster.
The port on the throttlebody is supposed to be connected to the charcoal canister(via the can purge valve in some cases) which filters fuel vapors from the gas tanks. IMO there is no good reason to disconnect this system, it's like intentionally throwing away some of the power producing potential of every tank of gas. Makes no sense, so if you want to put it back the charcoal can is usually right below the rad on the passenger frame rail.

 

Thank you, I have the canister purge solenoid, just haven't known where to put it until now. I agree, I don't understand why people disconnect these things. I think it is a misconception that you get more power or better gas mileage, I dunno.